[558] Ampullary Biopsies: Morphological Features and Useful Biomarker Panel of Adenocarcinoma and Adenoma A Single Institutional Experience on 273 Ampullary Biopsies

W Cao, J Liao, MS Rao, G Yang. Northwestern University, Chicago, IL

Background: In ampullary biopsy, diagnosis of adenoma or adenocarcinoma is morphologically challenged due to mix intestinal and pancreaticobiliary epithelium, inflammation, fibrosis and reactive change. It is necessary to find novel biomarkers to differentiating reactive epithelial change from adenoma or adenocarcinoma, Recently, High mobility group A2 (HMGA2) protein, one of the architectural transcription factors, has been found overexpressed in variety of tumors including breast cancer, non-small cell lung cancer, and pancreatic adenocarcinoma. -catenin and ki-67 are known, useful markers for malignancy. In this study, we systemically analyzed morphological features in 273 ampullary biopsies and used HMGA2, -catenin and ki-67 as a panel to evaluate malignancy.
Design: 273 ampullary biopsies from 2003-2007 were reviewed. HMGA2, -catenin and ki-67 immunostains were performed on the cases with marked reactive change, adenomas and adenocarcinomas under proper positive and negative controls. The result was considered as positive if more than 5% epithelial cells showed nuclear HMGA2 or ki-67 staining, cytoplasmic or nuclear -catenin staining.
Results: Of 273 cases, 55 cases (20%) displayed normal ampullary mucosa, 130 (48%) were benign reactive cases with inflammation, fibrosis, and reactive epithelial change, 62 (23%) were adenomas, 23 (8%) adenocarcinomas and 3 (1%) others. Within 130 benign reactive cases, 84 cases showed inflammation and/or fibrosis, 30 cases had focal pseudostratification and hyperchromasia similar to adenoma, 16 cases showed area of marked cytological atypical and mitosis suspicious for adenocarcinoma. The immunostains on the selected cases showed: 80% adenocarcinomas (4/5), 8% reactive cases (1/12) were HMGA2 positive. None of adenomas (n=12) were positive for HMGA2. Nuclear -catenin was found in 83% (10/12) adenomas, 100% (5/5) adenocarcinomas and 8% (1/12) reactive cases. Ki-67 showed normal staining pattern in the epithelia in the proliferative zone/crypts in reactive cases, but displayed diffusely increased expression in surface epithelia in all of adenomas and carcinomas.
Conclusions: Morphological diagnosis of ampullary biopsies can be difficult. Our results indicate that the panel of HMGA2, -catenin and ki-67 would be useful to differentiate benign reactive epithelial change from adenomas/carcinomas. HMGA2 is overexpressed in ampullary adenocarcinoma and may be served as a malignant biomarker for ampullary tumors.
Category: Gastrointestinal

Monday, March 9, 2009 1:00 PM

Poster Session II # 87, Monday Afternoon